In many surveying devices, the alignment of oriented optical measurement radiation is required, for example, by aligning components which integrate the beam path or by focusing on a target. In this case, this modification must be performed precisely and, in the case of dynamic applications, also sufficiently rapidly so that, for example, large masses to be moved are disadvantageous. In addition, field readiness of the measuring device fundamentally requires robustness of the drive and the bearings and low power consumption.
An industrial or geodetic surveying device generally has a standing axis and a tilt axis, which are mounted and driven. Examples of such measuring devices are total stations, theodolites, or tachymeters which—also together with integrated automatic target acquisition and target tracking units—are used for manifold surveying tasks, wherein both obtaining data and also solely checking, for example, in construction site monitoring, come into consideration. Other measuring devices are, for example, scanner systems such as laser trackers, laser scanners, or profilers, which record topographies of surfaces as three-dimensional point clouds in the scanning method.
The precision of the axes is distinguished above all by way of the bearings. The bearings must be dimensionally accurate, dimensionally stable, and shock resistant or protectable from shock. To be able to execute positioning actions in very small angle intervals with high precision, extremely low friction is additionally required, wherein in particular the friction force during the transition from adhesion to sliding is relevant.
In previous solutions, roller bearings and/or plain bearings were frequently used for the purpose of mounting. Such bearings require a relatively large amount of structural space, however, in particular also because usually at least one bearing must be installed for the axial mounting and one must be installed for the radial mounting. An increased constructive and manufacturing expenditure results due to this circumstance, and therefore higher costs. More masses are also moved due to the lack of compactness.